Biology 5B
What are Mendel’s Concepts?
1. Alleles exist
2. Individuals can be homozygous or heterozygous
3. One allele is dominant over the other
4. Gametes are haploid
A sperm or egg carries only one allele for each characteristic because homologous pairs separate during meiosis.
Law of Segregation
The inheritance of an allele for one characteristic does not effect the inheritance of an allele for a different characteristic
Law of Independent Assortment
How is sex determined in humans?
Sex chromosomes, the man’s genes
How many pairs chromosomes do humans have?
23
How many pairs of autosomes do humans have?
22
How many pairs of sex chromosomes do humans have?
1
a diagram used to show how a specific characteristic is passed through several generations in a family
Pedigree
a diagram used to show the possible gamete combinations from a genetic cross
Punnett Square the mating of an organism possessing a dominant phenotype but unknown genotype with an organism possessing a recessive phenotype
Test Cross
Mendel’s factors; units of heredity; sections of DNA capable of causing a trait
Gene
the trait which, when in the presence of contrasting trait, expresses itself
Dominant
the trait which, when in the presence of the dominant, doesn’t express itself
Recessive
the physical expression of an organism’s genes
Phenotype
the genetic make-up of an individual organism
Genotype
the particular site on a chromosome where a particular gene is located
Locus